gmod optimization

Best *basic* way:
- Create an HTTP CDN FastDL with bz2 compressed files.
- Or, create a workshop collection and have the users download that on join by adding the workshop collection to the downloads.

Best *advanced* way:
- Have some essential or large content downloaded on join via FastDL (bz2) or workshop
- Have a content downloader in-game download the rest while the player is in-game. There are a variety of addons/scripts to be able to do this